A privately owned island in the middle of the Illinois River, Bull's Island is a favorite spot for boaters, scuba divers, and plucky youth to take a dip. In the center of the island is a man-made pit, once a sand mine, that rapidly filled with spring water when the mining equipment hit a spring some 90-ish feet down. The pit was abandoned, (in the 60's I think) leaving an equipment shack, a bulldozer, and a crane underwater. Today the water is a white sand beach surrounding a crystal clear pond all set in the middle of the muddy brown Illinois River! You can see the bottom 20-30 feet down. It's cold down there! Have you brought up a handful of sand from the bottom of the raft chain?